FREQUENCY SYNTHESIZER

摘要

PURPOSE:To realize the frequency synthesizer in which a response characteristic of a loop filter for a high speed use is set in various ways by devising the characteristic of the loop filter to be switched for a low speed and a high speed. CONSTITUTION:A loop filter 4 consists of a lag/lead filter 5, a switch 9 and a bypass resistor 10. An output of a phase comparator 3 is connected to a capacitor 8 via the switch 9 and the bypass resistor 10. The loop filter 4 acts as a low speed use filter when the switch 9 is opened and acts as a high speed use filter when the switch 9 is closed. The loop response characteristic depends on the resistance of the bypass resistor 10.